Leather lubrication



Patented May 24,

rsr. oFFlcE 2,118,308 LEATHER LUBEIOATION Alphons 0. Jaeger, Mount Lebanon, has 'gnor to American Cyanamld & Chemical Corporation, New York, N; 8., a corporation of Delaware No Drawing.

Original application August '8,

1938, Serial No. 95,031. Divided and'tliis application All!!! 8, 1938, Sei'lal No. 95,032

18 Claims.

This invention relates to the oiling, stumng and fat-liquoring of hides. skins-and leather for the purpose of lubricating and finishing the same, and deals'primarily with new classes of materials for use in these processes. Objects of the invention are to provide an oil tanned or lubricated leather or skin which will be more resistant to light and oxidation and of more uniform quality than those finished by processes at present in use. A further object of the invention is the provision of new classes of materials for accomplishing the above purposes, which materials can'be manufactured in uniform quality from relatively inexpensive raw materials and will'not be subject to great fluctuations in market price. An additional object is the provision of leather containing these materials.

the absence of substantial amounts of water inorder to lubricate the fibers thereof. Perhaps the most important example, however, from a commercial standpoint is the process known as fat-liquoring, in which the hides after vegetable or mineral tannage are treated with an aqueous emulsion of an oil or fat for the introduction thereof. into the fiber of the leather. This step is used in the lubrication of upper leather, glove leather, and other light grades of vegetable or mineral tanned leathers such as those obtained by' chrome tannage, vegetable tannag'e, syntan tannage, iron tannage, formaldehyde tannage, formaldehyde-urea tannage, etc., either with or without a preliminary bleach.

The materials most commonly used in oil tannage, stufflng and fat-liquoring of leather are stated in Wilson The Chemistry of Leather Manufacture" to be glycerides of the animal or vegetable oil type such as olive oil, linseed oil, cod liver oil, coconut oil, menhaden oil, neats foot oil, moellon degras, etc. as well as free fatty acids such as the fatty acids of linseed oil, fatty acids of cod liver oil, etc. For use in stuffing and 'iat-liquoring, Wilson lists eight general classes of materials, namely, (1) true oils and fats; (2) soaps 'made from these oils and fats; (3) sulfonation products of these oils and fats; (4)

waxesy- (5) resins; (6) hydrocarbons; (7) Moellon Degras: and (8) eggyolk. Under the head-- ing of resins, colophony isthe only substance spethe physical characteristics and suitability of any one of them will be subject to variation in accordance with'its degree of purity. Even with these limitations, however, natural products of this type have been the only oils employed by the tanner, throughout the many centuries during which leather has been tanned and finished.

In my copending application, Serial No. 95,031, filed concurrently herewith I have shown that non-oleaginous esters of organic acids with alcohols possess the surprising property of lubricating the fibers of hides, skins and leather, and that all such esters oi sufliciently low vapor pressure may be used for this purpose. These esters may be used alone or'in solvents of low vapor pressure or, in some cases, of higher vapor pressures. The present application is a division of my above entitled application and claims specifically the tanning, fat-liquoring, filling and stuffing of hides, skins and leather'with special classes of esters or ester-like bodies of the above nature, as well as leather ta'nned or impregnated with these materials and the materials themselves. The esters or ester-like bodies of these classes are the nonoleaginous reaction products of organic acids in which a polyhydric alcohol radical is contained, with or without monohydric alcohol radicals or other substituents. These compounds form a wide field of tanning, fat-liquoring, filling and stumng materials which range from low vapor pressure liquids to solids and which may be used alone or together with plasticizers, solvents, diluents, emulsifying agents, and any other suitable auxiliary materials. Chemically they may range from esters having definite boiling points to plastic or solid resinous materials of more or less indefinite chemical constitution-which are preferably applied in the form of solutions, suspensions or emulsions. Irrespective of the exact constitution of these esters or ester-like bodies, however, I have found that they are all of great utility in the tanning, stufling, fat-liquoring and finishing of leather, and that new leathers of improved and unusual characteristics are obtained when they are incorporated therein.

It should be noted that some of the natural oils and fats which are listed above have also been used in unoxldimd or oxidized form in the field of paints, varnishes, lacquers and synthetic resins. These substances are, however, not plasticizers within the meaning 01' the term as it is used in the present specification. Accordingly the term non-oleaginous plasticizer" will be used tion, these being synthetic materials and characterized by the presence of a polyhydric alcohol radical and having a plasticizing action on hides, skins and leather, and containing radicals not present in natural oils and fats. The term nonoleaginous ester will be. used in defining some of the more limited aspects of the invention, and it is understood that both terms are used to exclude the natural oils and fats in their unmodified condition rather than as a limitation on the physical characteristics of the plasticizers and esters to which they refer.

It should also be noted that there is a large residual class of resinous materials which are not ester derivatives of the type falling within the scope of the present invention but which are well suited for use in conjunction therewith. Exam;- ples of these materials are coumarine and indene and their polymerization products, polymerization products of olefines, diolefines, acetylene, petroleum hydrocarbons, polystyrenes and the like, phenol-aldehyde condensation products, aldehyde-ketone condensation products, aldehydeamine condensation products, urea-formaldehyde condensation products, formamide-aldehyde condensation products, miscellaneous nitrogen containing resins, and vinyl resins, all of which may be used, alone or in. admixture, in conjunction with the materials covered by the present application for the tanning, stufilng, filling or iat-liquoring of leather. However, I do not claim in the present specification the use of these materials as such, since this formsthe subject matter of my copending application Serial No. 95,031, filed August 8, 1936.

Within the field of esters of organic acids containing polyhydric alcohol radicals there are many products of widely varying physical characteristics which range, according to the degree of reaction, from the hard, glass-like highly polymerized resins to soft oily or balsamic substances.- I'hese resins, balsams, and other esters may contain chemically combined mono-basic acids, or drying, semi-drying, or non-drying oils or the fatty acids thereof as modifying agents. Obviously, the less highly reacted esters, oils and resins, or those of more ready dispersibility in water or other inorganic or organic solvents or dispersing media, are more directly applicable to hides, skins and leather than are the more highly reacted resins. It shouldbe understood, however, that more completely reacted compounds such as the solid resins can also be introduced into leather, especially when they are combined or admixed with plasticizers such as those described in my copending application Serial No. 95,031, referred to above, or when they are dispersed in oils such as those referred to above as being in current use in the tanning industry. For this reason, the more highly reacted resins are by no means excluded from the present invention, but on the contrary these substances are included therein whenever they contain the radical of a polyhydric alcohol in combination with an organic acid.

As has been stated the low vapor pressure esters of organic acids with polyhydric alcohols possess, irrespective of their melting points at ordinary temperatures, the important property of lubricating and filling the fibers of skins and leather'to the same or greater extent than the stumng and fat-liquoring agents now in use, and these substances are particularly valuable for this reason. However, it has been found that the esters of certain organic acids with polyhydric invention.

' alcohols have more desirable'properties than do those of other organic acids. For example, I have found that the esters of the organic dicarboxylic and po'lycarboxylic acids are more desirable'fat-llquoring and stufling agents than are the esters of the mono-carboxylic acids, and

therefore they form a preferred, class of sub- 1 stance for use in practicing the invention. For

obvious commercial reasons the actions of the cheaper and more available organic diand polybasic acids have been more completely investigated than have the rarer and more expensive pimelic, suberic, azelaic, diphenic, naphthalic,

camphoric and adipic acids can all be used either singly or in admixture in the tanning, stufing and fat-liquoring of leather. This statement, however, should not be taken to mean that esters of the monocarboxylic acids are without utility in practicing the invention, for I have found that acids such as benzoic, benzoyl benzoic, stearic, salicylic, abietic and the like are also of advantage, particularly as modifying agents. It is understood, of course, that the above acids specifically enumerated are merely'representative of the classes to which they belong, all members of these classes being useful in practicing the invention, and that the corresponding substitution products and homologs of these acids such as the corresponding halogenation products, sulfonation products, nitro compounds, amido or amino or hydroxy compounds, etc. may be used in similar manner.

Another class of acids which are of importance in the preparation of lubricating and plasticizing esters for use in practicing the invention are those obtainable by the condensation of unsaturated acids with compounds containing a conjugated double bond system by the diene synthesis. Representative acids of this class are the hydroaromatic and terpenic monodiand polycarboxylic acids and their homologs obtained by the condensation of maleic acid and anhydride, acrylic acid, benzo-yl acrylic acid and the likewith unsaturated hydrocarbons such as butadienes, terpenes, cracked gasolines and the like, carboxylic acids such as abietic acid, and natural fats and oils and their modification products such as linseed oil, tung oil, castor oil and the fatty acids derived from these glycerides as will subsequently be described.

As the polyhydric alcohol, I may use ethylene glycol, diethylene glycol, propylene, butylene or i other glycols or polyglycols, or glycerol, polyglycand diglycerides obtained-from the natural oils and fats, preferably by heating with glycerol, since these retain many of the characteristics of the natural compounds now used in tanneries.

Esters produced by the reaction of any one or more of the above acids with any one or more of the above polyhydric alcohols, with or without modification by combination with monohydric alcohols or monobasic acids, may be used in the tanning, filling, stuifing or fat-liquoring of hides, skins and leather in accordance with the present Perhaps the most directly useful tion products of polyhydric alcohols with organic acids for use in the present invention are those which contain oils or oily materials as modifying class of reac- I agents, with or without additional esterificatiorl and fat-liquoring agents that have been used by the tanner. It is one of the chief advantages of the present invention that almost any of the oils and fats now in use by the tanner may be employed in producing oil modified resins, and these resins when applied to leather will impart all the lubricating properties of the oils themselves together with additional new properties which will be described.

The oil modified resins of the alkyd type are well known as a class and are described, for example, in Ellis The Chemistry of Synthetic Resins", vol. II, in considerable detail. In general they may be obtained by the monoglycerlde or'diglyceride process, in which triglyceride oils are heated with glycerine until the monoor diglyceride is produced, followed by reaction of these substances with organic polybasio acids, or

by other methods known in the art.

Suitable oil's, fats or fatty acids which may be 7 used for modifying alkyl resins of the above type,

or in the manufacture of oil modified resins of other types for use in the treatment of leather, include the vegetable oils such as those having drying or semi-drying properties, including linseed oll, tung oil, perilla oil, soya bean oil, China wood oil or rapeseed oil as well as non-drying oils such as cottonseed oils, palm oil, coconut oil, corn oil, olive oil, teaseed oil,- etc., and animal and marine oils, such as neats foot oil, cod liver oil, menhaden oil, moellon degras, commercial fish oil may also be used, either singly or in admixture. Frequently, it is of advantage to use the fatty acids obtained by the hydrolysis of these or other oils, as well as other fatty acids of high molecular weight and similar acids of oily or resinous character such as abietic acid. A special class of acids which are readily obtainable and are excellently suited for this purpose are those derived from tolloel or black liquor soap, which is produced as a by-product in the sulfite process or the Kraft process of paper pulp manufacture and consists of terpenes together with fatty acids such as oleic acid and stearic acid.

The resinous and balsamic compounds obtained upon introducing the above oils, fats and fatty acids into alkyd resins may be further modified by combination with any of the monohydric alcohols, such as those described in my co'pending application Serial No. 95,031, above referred to, or by combination with non-oil acids such as benzoic acid, acetic acid, furoic acid, propionic acid, tetrahydrobenzoic acid, etc.

Natural resins also form another class of modifying agents for synthetic resins, including such substances as rosin, copal, Congo gum and other fossil resins, and the use in leather lubrication of alkyd resins containing these substances as -modifying agents alone or with other modifiers is hydric alcohols, in which one or more of the fatty acid groups has been condensed with one or more unsaturated acids such as maleic acid, acrylic acid, benzoyl acrylic acid and the like by the diene synthesis. Some of the natural oils, such as tung oil and the fatty acids thereof, contain conjugated double bond systems which enable them to combine directly with unsaturated acids such as maleic acid, fumaric acid, acrylic acid or cinnamic acid by. the diene synthesis upon suitable heating. Other oils of this class, such as linseed oil, contain double bonds whichare not in con- Jugation, but which may be brought into conjugated positions during the course of the reaction and these may be made to combinein similar manner. Still other oils such as castor all contain hydroxy groups and upon dehydration of these groups by distilling in vacuo conjugated double bond systems are formed and the oils or their fatty acids can be made to undergo the diene synthesis with unsaturated acids. Other oils, fats and fatty acids, although partially or completely saturated and containing no conjugated double bond systems, can be treated with mild oxidizing agents such as potassium permanganate, hypochlorites, etc. to form compounds containing two or more hydro'xy groups and then dehydrated by heating or other means to develop unsaturated linkages which will permit condensation with unsaturated acids of the-type of maleic acid; All of these oils, fats and fatty acids, upon heating with the above mentioned unsaturated acids at varying temperatures which may range as high as 280 C., will combine togive an oil modified or fatty acid modified monoor poly-" basic acid complex having to a great extent the characteristics of the oils, but containing free carboxylic acid groups which can be further reacted with glycerol, glycols or other alcoholic constituents to form esters for use in the lubrication of leather. Condensation products of this class have been found to possess excellent filling, plasticizing and lubricating qualities when introduced into the fiber of hides, skins and leather, and

their use in these processes is an important feature of the present invention. Leathers filled, stuffed or fat-liquored with these substances are believed to be new products, and are also included in the invention.

Still another class of esters obtainable from the tained. All the esters of the above class, includ-- ing both those resulting from esterification with simple monobasic or polybasic acids and those of a more complex character in which the acid also forms a part of the molecule of a synthetic resin, form excellent lubricating, stufiing and fat-liquoring agents for hides, skins and leather in accordance with the presentinvention and are included therein. v

Among the polybasic acids which are used in the manufacture of unmodified and modified synthetic resins, phthalic acid and its anhydride occupy an outstanding position. Accordingly, res- I inous esters of this acid with polyhydric alcohols are of especial importance in the production of the filling, stuffing and'fat-liquoring agents of the present invention, both by reason of the high stage of commercial development which these resins have attained and also because of the cheapness and availability of the raw materials. A characteristic property of phthalic acid and its compounds which is of especial importance in the treatment of leather is their impenetrability by ultra-violet light, and the introduction of even the leather, in the form of unmodified or oil modified polyhydric alcohol esters, serves to give the leather a longer life and to prevent the decomposition and spewing of stuffing and fat-liquoring agents.

Among the oil modified resins which may be used in accordance with the present invention, those of greater oil length are of direct utility by reason of their ready dispersibility and similarity in action to the natural oils now used by the tanner. Any of the above enumerated oils may be heated or mixed with oil modified resins in this manner, and it is an advantage of the invention that the particular oils which have already become standard inany of the existing finishing processes may be extended with oil modified glyptals or other alkyd resins to improve their color, stability and resistance to ultra-violet light without material change in their essential stuffing and fat-liquoring characteristics. Typical compositions of this nature will be more fully described in the following examples.

It is understood that any of the esters or unmodified or modified alkyd resins of the above classes may be used, either singly or in admixture, in the tanning, filling, stuffing and fatliq'uoring of hides and leather. These compositions are well suited for use as the sole treating agent in these processes, but another important feature of the invention resides in their use in conjunction with the natural fats and oils which are now used for these purposes. This is important, not only by reason of the wider field of choice which is made available to the tanner by the use of a mixture of treating agents, but also because of the long experience which tanners have acquired with the natural oils and fats, which becomes available in applying the esters and condensation products of the present invention. When these products are used in conjunction with the natural oils and fats, their relative stability and the greater lu bricating properties which many of them possess will result in improvements in existing stuffing and fat-liquoring processes and will result in leathers of fuller and softer characteristics. This field of application of the invention is, of course, a

large one and the tanner will employ mixtures best suited to his own special needs.

Another feature of the invention which is of great practical importance resides in the modification of the polyhydric alcohol condensation products by the introduction of inorganic or organic substituents. For example, the sulfonation of many of these substances, or the use of sulfonated acids or oils in their preparation, results in increased emulsifying and penetrating properties, which are of great advantage in fatliquoring, and the introduction of nitro, amino, halogen and similar groups will also impart special properties. The most important .products of this nature are, of course, sulfonation products, as is shown by the fact that sulfonated alkyd or oil-modified alkyd resins may be used to substitute or supplement these sulfonated oils with great success. A particularly useful method of applying this feature of the invention is the partial sulfonation of the completed polyhydric alcohol esters, or the use of a mixture of sulfonated and unsulfonated acids in esterifying, whereby an incompletely sulfonated product is produced;

This feature of the invention permits the preparation of fat liquors having exactly the right emulsification and' penetrating properties for hides and skins of varying characteristics, as

small amounts of phthalic acid compounds into' well as for leathers which havebeen subjected to special tannages such as iron tannage, chrome tannage, aldehyde tannage, quinone tannage, alum tannage, etc.

Perhaps the most important field of application to leather of esters of polyhydric alcohols in accordance with the present invention is in the fat-liquoring of light leathers, either bleached or unbleached. These leathers, for example glove leather, upper leather, calf skins, etc., are usually subjected to chrome tannage or to a light vegetable tannage, and are frequently given an after bleachwith naphthalene sulfonic acid or other bleaching agents, such as those described in my Patent No. 2,029,322 in order to give a lighter shade to the leather. After these treatments, the leather would dry out stiff and hard, so it is drummed or otherwise treated in an emulsion of water insoluble fat-liquoring agent to lubricate and soften the fiber. In this process the lubricating properties of the polyhydric alcohol esters and particularly the unmodified and modified alkyd resins are of great advantage, and their use in this finishing step is a most important feature of the present invention. I have found, however, that it is sometimes necessary to add surface active agents to the polyhydric alcohol esters in order to produce the best emulsions for use in this process, and that this combination of ingredients will produce a fat-liquoring emulsion having hitherto unsuspected properties. Accordingly, these mixtures of alkyd resins and other esters with surface active agents, and the fat-liquoring emulsions prepared therefrom, I regard as new products of great utility, and these new products constitute another feature of the present invention.

A wide choice of surface active agents is available in preparing the stuffing and fat-liquoring mixtures constituting this feature of the invention, for almost any of the known classes of surface actlve agents may be successfully employed. Some of these surface active agents may be classified roughly as follows:

(l) sulfonated aromatic hydrocarbons and their homologs, such as sulfonated naphthalene, propyl or isopropyl, butyl or isobutyl and amyl naphthalene sulfonic acids, or their ammonium, alkali metal or triethanol amine salts.

(2) Salts of sulfonated aromatic or aliphatic esters of mono, diand polycarboxylic acids, such as dipropyl, diamyl, di-(methyl amyl) or di-octyl esters of sulfonated phthalic acid.

(3)Sulfated or sulfonated higher alcohols, such as sulfonated lauryl or other alcohols prepared from the fatty acids of vegetable oils.

(4) Sulfonated mineral, .veget'able or animal oils such as the Aquasols which are castor oil of varying degrees of sulfonation.

(5) sulfonated amides and imides of aromatic or aliphatic mono, diand polycarboxylic acids.

(6) Salts'of diene condensation products, such as the sodium, ammonium or triethanolamine salts of the condensation products of abietic and maleic or fumaric acids and their esters, salts and sulfonation products.

(7) Soaps of various fatty acids such as oleic, stearic, palmitic, and those obtained from talloel or black'liquor soap in wood pulp manufacture.

(8) Certain fatty acids and their monoor diglycerides such as wood spap fatty acids, glyceryl mono-ricinoleate, dl-glycerol oleate, etc. Sulfonated fatty acids may also be used.

(9) sulfonated terpenesand their condensation products such as pinene phenol sulfonate.

s,1 1s,sos I I re'sinsto the leather. and particularly during (10) Salts of phosphoric acid esters of higher alcohols or of phosphoric compounds of higher hydrocarbons. F

(11) Salts of quaternary ammonium compounds such as the ester of lauric alcohol wi chlorpyridino acetic acid.

Naturally, certain of the above surface active agents are more effective than are others for the emulsification of any given low vapor pressure polyhydric alcohol ester or mixture thereof, but- -all of the above classes of surface active agents will impart improved fat-liquoring properties to any of these esters in greater or lesser degree. In the following specific examples I have pointed out representative esters and representative surface active agents which have been employed with good results, and these will serve to indicate to the tanner the way in which the most suitable stuffing and fat liquoring compositions can be prepared for any particular leather which he may desire to finish. Insofar as the surface active agents containing sulfonic acid or sulfuric acid groups are concerned, which represent the most successful of the surface active agents which have been employed, it has been found that the products of a higher degree of sulfonation such as the 90% Aquasols, and other highly sulfonated vegetable oils and the like give better results when used in conjunction withlow vapor pressure esters and synthetic resins than do the less highly sulfonated products, and accordingly these form a preferred class of substances for use in conjunction with the present invention. However,

I the wide range of practical conditions dealt with in leather finishing, and the great number of types of leather involved make it difficult to state anything other than the most general principles involved in the selection of thebest surface active agents for use in conjunction with the low vapor pressure esters for any given purpose, and the ,tanner will naturally select those which he finds most suitable to his own finishing process.

by drumming orsimilar processes, in order to give weight and substance thereto. Frequently animal, vegetable and mineral oils are used inthis process to provide lubrication during the drumming of the leather and to prevent damage to the grain, as well as to provide additional lubrication to the leather fibers, and I have found that the polyhydric alcohol esters described above and particularly the oil modified glycerides of polybasic acids have a lubricating action on the fiber of the leather and are well suited for this purpose. Standard materials which have been used in the filling of sole leather are, for example, a mixture of cod oil, mineral oil and sulfonated oil together with filling materials such as sugar, Epsom salts and tanning extracts. Any or all of the above oily materials, either sulfonated or unsulfonated, may be modified or replaced, in

whole or in part, by the esters and other comstufling and fat-liquoring processes. it is sometimes desirable to alter or adjust their physical and/or chemical characteristics in accordance with the requirements'or different leathers and different steps inth'e process. This is preferably done by admixing, i s lving or extending these compounds with the synthetic plasticizers 'described and claimed in my copending application Serial No."95,03l, above referred to. For example, unmodified or oil modified alkyd resins may be plasticized by the addition of alkyl phthalates such as diethyl, dipropyl ordibutyl phthalates, whereby the viscosity is adjustedin such a manner that they are more suitable for use as filling and stuillng agents.

In the application of the synthetic resin and ester emulsions of the present invention to the oiling, stufilng and fat-liquoring of hides, skins and leather, any of the standard manipulative.

processes now in use may be employed. These processes are well described in the publication above referred to, and this description need not be repeated here. The most widely used method involves the introduction of the tanning, stufling or fat-liquorin'g agents into the hides by agitation in'a rotating drum, with or withoutv the continuous or intermittent application of a vacuum thereto, and the present invention is well suited for-use inconiunction with this, method of application.

In the following examples, the results obtained with representative compositions containing the do not constitute a limitation upon the invention in itsbroader aspects. Itshould also be noted that where, in these examples, a specific ester or resin is used in conjunction with a specific emulsifying agent, this is intended-to illustrate the results obtainable with these classes of materials and that equivalent materials from the same or different classes may be substituted without departing from the scope of the invention. The invention in its broader aspects is to be limited only by the scope of the claims appended hereto.

Example 1 A water emulsion containing 2% of dibutyl glycol diphthalate,'based on the weight of the leather, is prepared using 1%, of an emulsifying agent such as Aquascl AR which is 'a; highly sulfonated castor oil. This is readily done by agitating the ester for a few minutes and slowly adding a water solution containing the emulsifying agent with continuous stirring.

Chrome tanned calfskins are well washed and sometimes bleached for one hour, using ableaching agent such as "Tanak C which is a sulfonated diaryl methane condensation product. They are then fat-liquored in 'theabove emulsion by agitating in a drum for 1 hour at 60 (7., using 60% of their weight of'water and 3% of the lubricating material. The leather is then rinsed in water, set out and dried. Upon exami nation it is found that the finished leather is soft and flexible with a smooth, satiny feel on the grain side, but without odor and with none of vegetable or animal oils are used for this puright' from a. mercury vapor lamp for a period Bf hours together with similar samples which ad been fat-liquored with a standard vegetable 'sion. A remarkable difference in appearance s then noted; the samples containing the loqvegeta le oils had darkened appreciably while only a slight discoloration was apparent in the samples containing the phthalic ester.

Other phthalates such as the dimethyl glycol diphthalate, diethyl glycol diphthalate, dipropyl glycol diphthalate, diamyl glycol diphthalate, 'tributyl glycerol triphthalate, or diglyceryl phthalate tetracetate, or mixed esters of ethylene glycol and phthalic acid such as the methyl amyl, ethyl butyl, or 'similar compounds in which the free'carboxylic acid groups of the phthalic acid are esterified with different monohydric alcohols may be substituted for the dibutyl glycol diphthalates in the above example, with equally good results. Similarly, mixtures of these esters with each other or with natural fats and oils may be used. Because of the multiple phthalic acid groupings in these molecules they exert a remarkable stabilizing action on the natural fats and oils, protecting them from deterioration by the action of light and eliminating spew on the surface of the leather.

Example 2 Chrome tanned calf skins are fat-liquored in emulsions prepared as in Example 1, using 2% of glycol succinate, glycol maleate or glycol fumarate, respectively, together with 1% of Aquasol AR 90% as emulsifying agent. Good absorption of the lubricating materials was obtained and no surface deposition was noted.

Instead of the above simple esters, more complex compounds such as di-glycol maleate, di- 1 Example 3 In order to determine the relative value of various surface active and emulsifying agents, standardized water emulsions of these substances were prepared with dibutyl glycol di-phthalate, using the procedure outlined in Example 1. 1% of the emulsifier and 3% of the ester were used.

Calfskins were fat-liquored with these emulsions in the usual manner. The results obtained were as follows:

. Lubrication Ernulsilying agent E mulsion or leather Pinene phenol sull'onate Glyceryl ricinoleate Very stable Blackliquor fatty acid soaps Very stable. Di-glycol oleate Stable Isopit'opyl naphthalene sodium sulle- Wood soap fatty acids 'lwitehell oil 3X Sullonated vegetable oil Di-octyl sodium sulfosuccinate Very stable. Good.

Emulsions containing emulsion stabilizers such as gum tragacanth, colloidal clay and the like Samples of the finished leather were exposed together with emulsifying agents such as pinene phenol sulfonate were also prepared, using 3% of diethyl glycol diphthalate and 1% each of the emulsifying agent and emulsion stabilizer. Very stable emulsions were obtained which gave good lubrication to the leather.

From the above it is apparent that any emulsifying agent capable of producing a sufficiently stable emulsion of ester in water is suitable for use in fat-liquoring when used with or without the addition of an emulsion stabilizer;

Example 4 Chrome or vegetable tanned calfskins were washed well in running water and one-half of them were bleached at 50 C. for -1 hour with 3% Tanak, and washed well. Both the unbleached and the bleached skins were fat-liquored at 60 C. for 1 hour according to the procedure outlined in Example 1.

Representative emulsions were used containing resinous .esters of the following types, one bleached and one unbleached skin being fat-liquored in each emulsion. The resinous fat-liquoring agents contained the following ingredients:

They were prepared by heating together the materials indicated until the acid numbers had been brought to a suitable figure. The resins were then neutralized with ammonia in order to reduce viscosity and free acidity. Emulsions were made from the neutralized resins using Aquasol AR as an emulsifying agent and 3% of the resin-Aquasol mixture, based on the weight of the leather, was used for fat-liquoring.

Lubricating materials Ratio Lubrication Resin A Aquasol AR 90% l Resin r ass s esin Aquasol AR 90% Exhaustion of the fat-liquor was complete in all cases and was confirmed by the absence of a precipitate on acidification of a portion of the exhaust liquor with acetic acid. It will be noted from the above that resin C did not show results as favorable as resins A and B. This was due to emulsification dimculties, as was indicated by the fact that in 5 and 6, above, the leather was slightly sticky.

No appreciable difference was noted between the behavior of the bleached and the unbleached hides towards the fat-liquor. rials an equal degree of lubrication was obtained.

Example 5 In Example 4, the action or representative oil or oil acid modified resins in fat-liquoring was illustrated. These and other similar resins may be used. in simple admixture with the animal and vegetable oils now employed in fat-liquoring processes. I have found that improved fatliquoring results and greater stability are obtained, with elimination of spewing, when I use 'alkyd resins of the above or other types modified by chemical combination with fatty acids of such glycerides as animal and vegetable oils. For example, a non-drying vegetable oil such as teaseed ofl may be modified by the introduction of an alkyd resin made from phthalic anhydride, ma-

leic acid, succinic acid or the like with glycerine or glycols.

In order to form the monoglyceride of teaseed oil, a requisite amount of glycerine and some sodium carbonate as catalyst are added to a weighed amount of the oil which is heated to 270 C. and held there for about'10 minutes. The

. temperature is then dropped to 240 C. and the Two products were made in this manner, one

from 'phthalic anhydride and the other from maleic anhydride. They were emulsified with Aquasol AR 90% and used in the fat-liquoring of leather as in'the preceding examples, 3% of the fat-liquoring agent being used. Mixtures were employed as follows:

v Percent 1. Teaseed oil (unmodified) 1 Aquasol AR 90% 2 2. Teaseed oil (unmodified) 2 Aquasol AR'90% 1 3. Teaseed oil-phthalic glyceride resin 1 -Aquasol AR 90%"; 2 4. Teaseed oil-phthalic glyceride resin 2 Aquasol AR 90% 1 Teaseed oil-phthalic glyceride resin 3 Neutralized with NHiOH 6. Teaseed oil-maleic glyceride resin 1 Aquasol AR. 90% 2 7. Teaseed oil-maleic glyceride resin 2 Aquasol AR 90% 1 8. Teaseed oil-maleic glyceride resin Neutralized with ammonia 3 Erample 6 Leather was fat-liquoring in the usual manner using 3% of resin modified teaseed oil and 1% of aul-ionated teaseed oil as an emulsifying agent, based on theweight of the leather used, but at extremely great oil lengths. In other words, an extremely high ratio of oil to resin was used. The

term oil length" is used to indicate the number With both mate! 1. Teaseed oil-phthalie glyceride resin oil length 1000 2. Teaseed oil-phthalic glyceride resin oil 'length'l'l80 3. Teaseed oil-phthalic glyceride resin oil length 3570 Corresponding glycol resins, prepared by substituting glycol for glycerine in the process of Example 5, were used of the following oil lengths: 4. Teaseed oil-phthalic glycol I resin -oil length 495 5. Teaseed oil-phthalic glycol resin oil length 1000 6. Teaseed' oil-phthalic glycol resin oil length 2050 In all cases the fat-liquors were completely exhausted and the degree of lubrication was excellent, showing that the introduction of even relatively small amounts of a synthetic resin will accomplish the objects of the present invention.

This example illustrates fat-liquoring. agentsprepared in accordance with the present invention which are of great attractiveness, as it is apparent that any of the glyceride oils now used in the filling, stufling or fat-liquoring of leather may be modified by this procedure. It is only necessary to react the oil with relatively small amounts of glycerol, glycol or other polyhy'dric alcohol and then heat with the desired poiybasic acid, or alternatively, to react a portion of the oil with the glycerol or glycol and acid and then heat with the remainder of the oil before the reaction has come to completion. In certain cases it may be desirable to react all the ingredients simultaneously.

Example 7 with other known or approved filling agents, such as those at present employed for this purpose. For example, in many tanneries a mixture of cod oil, mineral oil and sulfonated oil together with filling materials such as sugar, epsom salts or sulfite cellulose extract are drummed into the moist leather, the oils providing lubrication during the drumming procedure to prevent-damage to the grain and also to lubricate to some .extent the fibers of the finished leather. Partial or complete replacement of the oils now used by long oil resins, such asthose described in Example 6, will result in the production of a leather having the follow ing advantages:

Less washout loss Greater water resistance Better color Higher resistance to oxidation Greater thickness (more iron") without increase .in water As an example, leather saturated with water is tumbled for 10 minutes in a water dispersion of epsom salts and sulfite cellulose extract, after which a charge containing sugar, resin and oil previously mixed and heated to 60 C. is added.

Tumbling is continued for 30 minutes, after which the process is complete. Resins prepared-in the followingmanner were used in the above mixture, the parts being given by weight.

Parts The cod oil and rosin were heated to 120 C. for 10 minutes, the mineral oil and corn sugar were added and the mixture heated to 105 C. until homogeneous.

(2) Made in a similar manner using--.

Parts Cod oil 5 Mineral oil 5 Resin B (see Example 4) 5 Corn sugar 10 Turkey red oil 2 (3) Made in a similar manner using- Parts Resin B (see Example 4) 5 Corn sugar l Mineral oil 10 Turkey red oil 1.5 (4) Parts Gum rosin 2t5 Resin B (see Example 4) 2.4 Mineral oil 10 Corn sugar 15' Turkey red oil 1.5

() Made in a similar manner using- Parts Mineral oil 15 Gum rosin Cod oil 5 Corn sugar Turkey red oil 1 All of the above materials were taken up more or less completely by the leather and the surface of the leather was clean. The cut of the leather was good and the feel satisfactory, showing that leather of satisfactory fullness was obtained.

Example 8 gums, waxes and the like in order to add fullness and flexibility thereto.

For example, sole leather is placed in water at 40 C. for minutes or until completely wet through and is then placed in a rotatable drum provided with a liquid inlet and outlet in the axis thereof.

Dibutyl glycol diphthalate is cut with diethyl phthalate until its viscosity is sufficiently reduced and the mixture is charged into the drum, which is then rotated until 3-5% of the charge-has been taken up by the leather. This treatment produces a leatherwhich is well lubricated and which shows excellent resistance to deterioration under the action of ultra-violet light.

With very heavy leathers it is sometimes desirable to add.5-10% of sulfonated teaseed oil or sulfonated castor oil to the above charge in order to obtain a more uniform penetration.

In some cases it may be convenient to employ a volatile solvent in drum stuifing instead of plasticizers of the low vapor pressure type as exemplified by diethyl phthalate. In such cases a more complex stufling agent such as aceto-glyceryl butyl phthalate may be dissolved in benzol or" ethyl alcohol and introduced into the drum in place of the above described mixture.

Synthetic resins of a non-crystalline or plastic nature may also be introduced into the leather as stufling agents. For example a resin prepared by heating together a mixture containing 330 parts by weight of rosin, '70 parts glycerol and 45 parts maleic acid at temperatures of 230-250 C. may be introduced in the above manner, either alone or in admixture with dibutyl phthalate or other suitable plasticizers, and may be thinned to a suitable consistency if necessary by the addition of a mineral hydrocarbon solvent. Similarly, mixed resins may also be used, such as a mixture of the above resin with equal parts of an unmodified phthalic glyceride resin, the two materials preferably being melted together in order to obtain a more homogeneous mixture.

Many of the ester products of the present invention are also well suited for hand stufllng. Compounds which may be introduced in this manner, preferably after warming to increase fluidity or in admixture with esters of sulfonated acids such as di-octyl or di- (methyl amyl) sodium sulfosuccinate, dihexyl sodium suifophthalate and the like are, for example, the glycol and glyceryl esters of organic dibasic acids such as glycol succinate, di-glycol succinate, di-glycol fumarate, di-glyceryl maleate, di-methyl-diethylene glycol di-furmarate and di-butyl glycol (ii-phthalate. which may be used alone or in admixture with each other or with the above mentioned impregnating and surface tension reducing agents. These compounds and their mixtures may also be used in admixture with many of the unsulfonated and sulfonated vegetable oils, flsh'oils and animal oils.- now used for this purpose.

Example 9 A somewhat less expensive class of .filling and stufiing agents falling within the scope of the invention are those obtained by the stabilization of vegetable and animal oils by means of a polyhydric alcohol derivative of an aliphatic or aro- -matic dicarboxylic acid. For example, oil exing constituent is extended with teaseed oil on other stufflng or fat-liquoring oil such as cod oil, menhaden oil, neats-foot oil and the likeby heating the resin at 200 C. with sufficient quantities of these oils .to give a final resin complex containing from 5 to 40% phthalic glyceride. The products obtained vary inconsistency from viscous oils to plastic masses and may be used in directreplacement of the fat-liquoring and stuffing oils now in use or in admixture with these substances. The use of these resinous materials improves the initial color of the leather obtained and protects the leather against rancidity and premature deterioration.

When glycerides of maleicand fiunaric acids are used in the above preparations instead of or in admixture with the phthalic glycerides, the products obtained are even more resistant to the development of bacterial and fungus growth.

Leather of increased water resistance is obta'ined when resinous materials of the above nature' containing drying oils such as linseed oil or oils may be used to replace those mentioned above, in whole orin part, in the the resin-oil complex.

Example 10 A special class of polybasic acids which may be esterified with polyhydricalcohols for the preparation of plasticizing esters for use in the lubrication and preservation of leather in accordance with the invention are those derived from the diene synthesis. These acids are prepared by condensing an unsaturated acid or acid-forming compound containing'the group with a compound which contains or develops during the reaction one or more systems of conjugated double bonds of the type By heating together or otherwise reacting these preparation of components in the absence or presence of condensingagents or inert materials such as solvents,

cyclic acids of a hydroaromatic nature are obtained which upon further treatment iorm plasticizers which are well suited for leather finishing.

Among the unsaturated. acids and. acid-form= ing materialswhich may be condensed in this mannermaleic acid and anhydride, fumaric acid and acrylic acid are perhaps the most important commercially, but other acids of this nature may also be used. For example itaconic acid, citraconic acid and crotonic acid and unsaturated acids of the aralkyl type such as cinnamic acid may be employed. In general any unsaturated mono or polycarboxylic acid containing the above mentioned grouping may be used, either in the pure state or in admixture with other substances.

A wide range of compounds containing the diene or conjugated double bond linkage are known and can be used for condensation with unsaturated acids of the above character, and this class includes compounds such as terpenes which develop such linkages duririg the reaction. When simple hydrocarbons such as butadiene or hydrocarbon fractions containing this s'ubstance or other hydrocarbons containing one or more con jugated systems of double bonds, for example cracked gasoline, are condensed with maleic or iumaric acid a product containing a tetrahydrophthalic nucleus is obtained which, when reacted with monohydric or polyhydrlc alcohols or their mixtures is well suited for use in accordancewith the invention. similarly, hydrocarbons such as cyclopentadiene, 'cyclohexadiene, phelland'rene, myrcene, isoprene, dimethyl butadiene, phenyl butadiene, methyl phenyl butadiene and the like may be reacted with any of the above mentioned unsaturated acids to yield derivatives of phthalic, benzoic and other cyclic acids which form esters having excellent properties for the lubrication of leather. Other hydrocarbons which are readily obtainable and are well suited for use are the acetylene polymers produced by the absorption of acetylene in ammoniacal cuprous chloride solution such as the acetylene tetramer 1,5,7 octa- -triene-3-ine, and coumarone and indene obtained from coal tar distillates, all of which can be condensed with maleic, iumaric, or other similar un= above substances may be reacted with the unsaturated acids which have been described to produce acids which can be partially or completely reacted with polyhydric alcohols, glycols, monoor diglycerides and the like to produce excellent stumng, filling and fat-honoring agents for hides, sizins and leather in accordance with the inven-, t on.

' A class of compounds which are particularly well-suited for use in the lubrication of leather are the esters of acids obtainable by the condensation of maleic, iuinaric or other unsaturated acids of the above described class with the natural oils and the products obtainable therefrom. Manyof these oils, such as tung oil, linseed oil and the like, are the glycericles of fatty acids which contain or develop conjugated double bond systems and such oils, or the fatty acids obtained therefrom, may be directly condensed with the unsaturated acids by simple heating to temperatures of 150- 2ilil C. Other oils, such as castor oil and 'perilla oil, can be modified by dehydration into products containing such doubleb'ond systems. Still other oils, such as fish oil, teaseed oil, neats-foot oil, mineral oils and the like, must be subjected to more extensive treatment to convert them into products capable of reacting with unsaturated acids by the diene synthesis, as by halogenation and subsequent dehalogenation, treatment with permanganate solutions and subsequent dehydration, etc. In all cases, however, the resulting cyclic acid derivatives when esterified show great- 1y improved qualities of stability and resistance to spewing and rancidity in comparison with the original oils from which they were prepared, and are well suited for the purposes of the present invention.

As an example of the above, tetrahydro-ophthalic acid obtained by the condensation of,

equimolecular quantities of maleic acid and butadiene is esteriiled with ethylene glycol and an emulsion containing 2% of the product and 1% oi" equally ood results.

As an example of natural oils, tung oil is mixed with maleic anhydride in equimolecular proportions and the mixture is heated to 180 C. The resulting condensation product after esterification with glycol monoacetate is mixed with Aquasol AR 90% using a ratio of ester to Aquasol of 5:1, and 6% of themixture is used .in the form of an emulsion to fat-liquor bleached and unbleached chrome leather in the following manner:

Chrome tanned calfslsins are washed in running water and treated with the fat-liquoring emulsion, some with preliminary bleaching at 50 C. for one hour with Tanak A and others in the unbleached state. The fat-liquoring was continued for one hour at 60 C. with an emulsion containing 60% water and the lubricating materials. After fat-liquoring the leather was rinsed in warm water, set out, dried and examined for degree of lubrication and color. Leather iatliquored with the original untreated oils was also prepared by corresponding treatment and was compared with the condensation products for light resistance.

Similar fat-liquors were prepared using the following esters and chrome tanned calf leather was lubricated according to the above described procedure:

Tung oil maleic anhydride condensation product, glycol mono-butyrate ester Tung oil fumaric acid condensation product, glycol mono-acetate ester Castor oil maleic anhydride condensation product, glycol mono-acetate ester L Linseed oil maleic anhydride condensation product, glycol-mono-acetate ester In all cases a. satisfactory degree of lubrication of the leather was obtained and the color of the leather was good. Good exhaustion of the fatliquoring baths was obtained.

Representative samples of each of the above leathers were tested for resistance to ultraviolet light in comparison with corresponding samples fat-liquored with the untreated oils by exposure to light from a sun lamp for several hours. In all cases the pieces fat-liquored with esters of the condensation products showed less discoloration than those fat-liquored with the natural oils.

What I claim is:

1. The method of fat-liquoring, filling or stuffing hides, skins and leather which comprises introducing into the same a relatively water-insoluble plasticizer containing a polyhydric alcohol ester of an organic carboxylic acid selected from the group consisting of aromatic monoand polybasic acids, hydroaromatic monoand polybasic acids and aliphatic polybasic acids.

2. The method of fat-liquoring, filling or stuffing hides, skins and leather which comprises introducing into the same anester of a polybasic organic carboxylic acid and a polyhydric alcohol.

3. The method of fat-liquoring, filling or stuffing hides, skins and leather which comprises introducing into the same a relatively water insoluble reaction product of an organic polybasic acid and a polyhydric alcohol together with. a solvent softener capable of lowering the viscosity thereof.

4. The method of fat-liquoring, filling or stuffing hides, skins and leather which comprises introducing into the same a dispersion of a rela-' tively water insoluble plasticizer containing a polybasic acid combined with a polyhydric alcohol radical in a natural fat or oil.

5. The method of fat-liquoring, filling or stufiing hides, skins and leather which comprises introducing into the same a low vapor pressure ester of an aromatic carboxylic acid and a polyhydric alcohol.

6. The method of fat-liquoring, filling or stufiing hides, skins and leather which comprises introducing into the same a relatively water insoluble, ester of an aromatic polybasic acid with a polyhydric alcohol.

7. The method of fat-iiquoring, filling or stuffing hides, skins and leather which comprises inauasoa troducing into the same an ester or a phthalic acid with a polyhydric alcohol.

8. The method of fat-liquoring, filling or stufiing hides, skins and leather which comprises introducing into the same a polyhydric alcohol ester of an aliphatic carboxylic polybasic acid.

9. The method of fat-liquoring, filling or stufiing hides, skins and leather which comprises introducing into the same a polyhydric alcohol ester of an aliphatic polybasic acid selected from the group consisting of maleic acid, its isomer Iumaric acid, and its reduction product succinic acid.

10.'The method of fat-li'quoring, filling or stufiing hides, skins and leather which comprises introducing into the same a polyhydric alcohol ester of an organic acid obtained by the condensation of an unsaturated organic acid containin the group. I v

- C=CC'0 with a compound which contains or develops during reaction a system of conjugated double bonds of the type 11. The method of fat-liquoring, filling or stufllng hides, skins and leather which comprises introducing into the same a polyhydric alcohol ester of a monobasic acid of fish, animal or vegetable oil origin which has been modified by condensation by the diene synthesis with an unsaturated acid containing the group 12. The method of fat-liquoring, filling or stufiing hides, skins and leather which comprises introducing into the same an oil modified alkyd resin containing an ester of an aromatic carboxylic acid.

13. A method of fat-liquoring hides, skins and leather which comprises contacting them with an aqueous emulsion containing a relatively water insoluble plasticizer containing a polyhydric alcohol ester of an organic carboxylic acid selected from the.group consisting of aromatic mono.- and polybasic acids, hydroaromatic monoand polybasic acids and aliphatic polybasic acids.

14; A method of fat-liquoring hides, skins and leather which comprises contacting them with an aqueous emulsion containing a relatively water insoluble plasticizer comprising a polyhydric alcohol ester of an organic polybasic acid.

'15. A composition suitable for fat-liquoring, filling .or stufiing hides, skins and leather comprising "a, polyhydric alcohol ester of an organic polybasic acid and a surface active agent.

16. A composition suitable for fat-liquoring, filling or stufiing hides, skins and leather comprising a normally liquid plasticizer containing an ester of a polyhydric alcohol withan organic carboxylic acid selected from the group consisting of aromatic monoand polybasic acids; hydroaromatic monoand polybasic acids and aliphatic polybasic acids and a surface active agent.

17. Hides, skins and leather containing a water-insoluble plasticizer comprising a polyhydric alcohol ester of an organic carboxylic acid selected from the group consisting of aromatic monoand polybasic acids, hydroaromatic mono-, and polybasic acids and aliphatic polybasic acids.

l8. Hides, skins and leather containing a water insoluble polyhydric alcohol ester of an organic polybasic acid.

ALPHONS O. JAEGER. 

